1. Field of the Invention
The present invention relates to improvements in a heat pump type air conditioner applied to an automotive vehicle, and more particularly to an improvement of a working capacity of a heat pump type air conditioner.
2. Description of the Prior Art
It is well known that a heat pump type air conditioner is applied to an automotive vehicle and provided with a four-way valve for changing refrigerant flow in a heating drive and a cooling drive. During the heating drive, an outer heat exchanger is used as a heat absorber and an inner heat exchanger is used as a radiator. On the other hand, during the cooling drive, the outer heat exchanger is used as a radiator and the inner heat exchanger is used as a heat absorber. Such a heat pump type air conditioner is disclosed, for example, in Japanese Patent Provisional Publication No. 2-290475 and Japanese Utility Model Provisional Publication No. 2-130808.
As shown in FIG. 22, during a heating drive a four-way valve 2 is set as indicated by a continuous line in FIG. 22 and refrigerant is circulated as follows: A compressor 1.fwdarw.the four-way valve 2.fwdarw.a first inner heat exchanger 3.fwdarw.heating heat exchanger 4.fwdarw.a second inner heat exchanger 5.fwdarw.an expansion valve 6.fwdarw.an outer heat exchanger 7.fwdarw.the four-way valve 2.fwdarw.receiver 8.fwdarw.the compressor 1. Accordingly, the heat of the refrigerant is transmitted to air, led by a blower fan 9 and used for heating a passenger compartment. The heat from an engine 10 is transmitted to the refrigerant through the heating heat exchanger 4 and further transmitted from the refrigerant to air led by a blower fan 11 for heating the passenger compartment. The heat of the air led by a fan 12 is transmitted to the refrigerant through the outer heat exchanger 7.
On the other hand, during a cooling drive, the four-way valve is set as indicated by a dotted line in FIG. 22 and refrigerant is circulated as follows: The compressor 1.fwdarw.the outer heat exchanger 7.fwdarw.the expansion valve 6.fwdarw.the second inner heat exchanger 5.fwdarw.the first inner heat exchanger 3.fwdarw.the four-way valve 2.fwdarw.the receiver 8.fwdarw.the compressor 1. Accordingly, the heat of the refrigerant discharged from the compressor 1 is radiated into the atmosphere by the first inner heat exchanger 3, the heat of air led by blower fans 9 and 11 is radiated to the refrigerant by the first and second inner heat exchanger 3 and 5, and the cooled air is supplied into the passenger compartment.
With such a conventional air conditioner, the absorbed heat amount by the outer heat exchanger 7 is decreased during the heating drive under a weather condition such that the ambient temperature is low, the automotive vehicle is in running, or it is raining or snowing. Furthermore, if the workload of the compressor 1 is constant, the radiated heat amount from the first and second inner heat exchanger 3 and 5 which radiate the sum of the heat absorbing amount from the outer heat exchanger 7 is decreased, and the heating capacity of the air conditioner is lowered. Additionally, the lowering of the heating capacity invites the frost to the heat exchanger. This increases a defrost drive and prevents a stable heating drive. Furthermore, in order to prevent fogging of windows in the automotive vehicle, both of the cooling and heating drives are often carried out even in the winter season.
However, the heat pump type air conditioner can not simultaneously carry out both cooling and heating, and therefore it is necessary to use other heat source such as exhaust heat from the engine 10 to carry out the above mentioned defogging operation. Accordingly, such a conventional heat pump type air conditioner can not be sufficiently operated if applied to a vehicle having no heat source such as to a solar car or electric vehicle.